Improvement in cement roofs



UNITED STATES ABRAHAM STRAUB, OF MILTON, PENNSYLVANIA.

IMPROVEMENT IN CEM ENT PtOOFS.`

Specification forming part of Letters Patent No. 38,065, dated March 31, 1863.

.To @ZZ whom it may concern.-

Be it known that l, ABRAHAM STRAUB, of Milton, in the county of Northumberland and State of Pennsylvania, have invented a new and useful Improvement in Cement Roofs for Buildings; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the accompanying drawings, making a part of this speciiication, in which- Figure 1 is a vertical section on a central longitudinal line of one of the rafters of a roof having my improvement applied; and Fig. 2, a plan view of the same as it appears before the cement is applied thereto, like letters indicating the same parts when in both figures.

The nature of my invention consists, substantially as hereinafter described and specified, in dispensing with the use of the felting or cloth heretofore required between the sheeting and the resinous cement by grooving the upper side of the sheeting-boards, reducing them to comparatively narrow widths, and securing them closely together upon the rafters by tonguing, groovin g, and nailing, so that in afterward applying the cement in a melted state as usual for the reception of the hot sand or gravel the said grooves in the surface of the sheathing will become filled therewith and any cracks or openings which may afterward occur in the boards thereof from changes in the weather or from seasoning will be compelled to take place in the said surfacegrooves containing the tenacious cement, and thus the required continuity of the weather-surface of the roof be preserved.

In the drawings, AA are the usual rafters; B B, the board sheathing, and b b2 the surface-grooves in the same; C C, the nails which hold the sheathing-boards down upon the rafters; D D, the cement, and E the sand or gravel adhering to the surface of the latter. The sheathing-boards B should not be more than ve or six inches in width each after they have been tongued and grooved'at their edges, and the shoulder at the upper side of the tongue of each board should be cut back about a quarter of an inch fart-her than the shoulder below it, so that when the said boards are united together and nailed down upon the rafters A there will be left a groove, b2, about a quarter of an inch wide directly between the upper edges of each two adjoining boards, while along in the'middle of each board B another groove, b', or more, substantially of the same width, is made, as represented in Fig. 1. These grooves should be about half an inch in depth, supposing the sheathingboards to be of the usual thickness of one inch; consequently the tongues and grooves in the edges of the boards will be nearer to the under sides of the boards, as seen in the same gure. The boards B are laid horizontally across the rafters A, substantially as in flooring, and are secured thereto by the nails C, by driving one into each rafter A, through the middle of the space which is between each pair of the grooves b b2, and then the usual barge boards F applied to their ends. The cement D is then -melted and applied hot in the usual manner, so that it shall fill the grooves b b2 and also coat the surface of the sheathing for the reception of the hot gravel or sand E in the usual manner. In the operation of this sheathing during the changes ofthe weather and in seasoning, the nails C will rmly keep the middle of the thick portions of each of the boards B in its original position on the rafters A, and whatever shrinking or variations in width may occur in any board B will take place within the narrow space which is between a longitudinal row of the nails C and the groove on either side of it, and if a crack or split occur in consequence it must take place in the groove because of the comparative thinness and weakness ofthe board at such point; but, as the said groove is filled with the pliable and adhesive cement D, the latter will hold firmly to the wood and yield to its variations withoutpartin g or breaking, and will therefore keep the said crack or split in the sheathing beneath it covered and effectually prevent leaking. As the groove b2, which is between every two of the boards B, is formed directly in contact with the tongues which unite the boards, the effect of any vari ations in the widths of the boards B upon the said grooves will be to move the tongues slightly outward or inward within the grooves; but still the protecting operation of the cen'ent D in the surfacegroove b2 above it will be the same as that described as taking place in the middle grooves, b. In the course of time, should the cement become so hard as io entirely lose its tenacity, and therefore be come liable to crank or to separate from the Wood, the application of a thin coat of fresh hot cement will revive it and remedy the den fect.

Aside from the greater comparative durability,` and strengthening effect upon the building afforded by this sheathing, the grooves being horizontal, necessarily prevent the ceinent from iiowin g down the roof in hot Weather, and therefore permit the application of -cement and gravel rooting to roofs of greater angles of elevation than Where the felt or cloth is used as the immediate foundation for the cement, as hitherto, While the original cost of this myimproved sheathing is not any more than that consisting of the rough boards vcovered With the usual strata of felt or cloth.

A I do not intend to confine the construction oi' the sheathing-boards B andthe surfacegrooves b b2 therein to the precise Widths,

number, and depths described, as it is obvi- A. STRAUB.

Vitnesses:

JNO. MILLER, A. B. HENDERsoN. 

